I've pm'd the chap over at babybmw about how to code in the fan timer. If your car has the electric heater matrix then it should be possible to defrost the car by timer! Lovely!!

The heater (ordinarily) will not work without the engine on to provide enough current. Is he proposing to disable all the energy-monitoring stuff? Sounds like a recipe for disaster - if it were easy to do then BMW would do it along side the preconditioning timer.

Wish the 535i had the PTC heater, it is the only negative about the car. Miss the fact the 330d diesel, like your car, would start giving cabin heat almost immediately.

Now when I get to the next village (3-miles) and ECT is about 53 - 55C (similar to the diesel at around freezing temperatures) I'm no where near at the same cabin heating. It is just warm, where the 330d would be pumping out loads of heat and even adjusting the face vent temperature back to cooler levels.

The heater (ordinarily) will not work without the engine on to provide enough current. Is he proposing to disable all the energy-monitoring stuff? Sounds like a recipe for disaster - if it were easy to do then BMW would do it along side the preconditioning timer.

I have no idea. I assume as with most coding of options it's just a case of telling the car that to enable it. If the electric heater won't work without the engine running then I assume it'll just blow cold air through, needing the diesel heater to create heat - which it won't have.

Perhaps but what I'm saying is as standard you can set the fans to come on at a certain time so if it was not detrimental to also have the electric heater on then BMW would have given the function as it would be very useful. I suspect though that to get any decent heat the heater will need to be 250W if not more, which would draw 20A. On a cold day that would kill the battery pretty quickly so there is a good reason why BMW deny this functionality. You might be able to code it out but is there any point getting to a defrosted car that won't start?

Perhaps but what I'm saying is as standard you can set the fans to come on at a certain time so if it was not detrimental to also have the electric heater on then BMW would have given the function as it would be very useful. I suspect though that to get any decent heat the heater will need to be 250W if not more, which would draw 20A. On a cold day that would kill the battery pretty quickly so there is a good reason why BMW deny this functionality. You might be able to code it out but is there any point getting to a defrosted car that won't start?

Exactly, with a larger draw than you suggest as well. BMW data states the following for the E87 & E9x models.

Quote:

The only power that is available to the electric auxiliary heater is the excess power from the alternator. The maximum heat output available is 1250 watts. At maximum heat output, the current draw is limited to 74 amperes (± 10%). The electronic circuitry in the electric auxiliary heater automatically adjusts to the respective minimum. (Request of the IHKA and limitation by the DME.)

Even in use the auxiliary element can be switched down, if the current available is not enough. It is like many functions including heated rear demister and heated seats, it is in the list for % function and/or clocking if the power available is too low.

So like you, I can't see any way it can be coded without messing with the energy management bigtime.

I'll add another comment about the amount of heat we need to warm a car.

I've used an electric fan heater (for many years) to thaw out my cars on frosty days.

I run a 2kW heater and it takes about 30 minutes to thaw all windows and put a reasonable amount of warmth in the cabin. That's at around -2C ... in a 3-series touring. It uses a Kilowatt's worth of energy to do the job! Get it any colder and that increases dramatically. 5-series touring takes another 15 minutes to do a similar job as in the 3-series.

So any idea a small amount of battery drain, say 'one chain' in the PTC element will do much good, over a short amount of time, forget it as a serious way to preheat the car.

You can see why BMW doesn't even entertain using the PTC element as a pre-heater. You need the diesel fuelled pre-heater to do a fast job, as they can give out a few kilowatts quite fast. But as said, not an option on the UK 3-series models.

But the heater is still useful to demist windows quickly once you have the engine running. It would be unfeasible to expect it to noticeably "warm" the car though.

Agree, but as it does work fast(ish) for the initial demist, I see trying to use a timer for use ahead of the start, is one complex operation for possibly very little gain. Simply on the energy demands being so high. Any system to use it would still need battery protection, so can imagine it not working on the days you need it.

I noted on my 3-series that some winter cold starts there was definitely restrictions on the electrical system, rear screen demister and/or the auxiliary element would be clocked, it was a sign my car needed the battery on a trickle charge. I'm not talking of an old battery either, noticed the function when the car was relatively new. Shows how close we can sail to the wind on electrical demands during the winter months.

Agree, but as it does work fast(ish) for the initial demist, I see trying to use a timer for use ahead of the start, is one complex operation for possibly very little gain. Simply on the energy demands being so high. Any system to use it would still need battery protection, so can imagine it not working on the days you need it.

I noted on my 3-series that some winter cold starts there was definitely restrictions on the electrical system, rear screen demister and/or the auxiliary element would be clocked, it was a sign my car needed the battery on a trickle charge. I'm not talking of an old battery either, noticed the function when the car was relatively new. Shows how close we can sail to the wind on electrical demands during the winter months.

Mine had a picture of a fan - when you selected that you entered the time you wanted the fan to come on.

Ok I've coded it and I get that icon too now along with the option for heater AND blower when I put the time in.

Not sure exactly how it works. I gave it a try and it just seems to blow forward when the time comes. Any idea how to set it up to blow towards the screen? Even if it's not heated, it;s better than nothing I guess. Mind you, the guy over at babybmw reckons it comes through warm. Maybe the car knows that the engine isn't running and just supplies enough juice to the heater to take the chill off? It's pretty smart after all!